The scope of this proposal includes a study of dietary factors which affect lipid metabolism and atherosclerosis in the baboon (Papio ursinus) and Vervet monkey (Ceropithecus aethiops pygerethrus). We propose to use a semi-purified, cholesterol-free diet which may be regarded as a model of endogenous hyperlipidemia. We will examine the effects of animal (casein, lactalbumin) versus vegetable (soy protein, wheat gluten) protein in diets in which the carbohydrate (sucrose) and fat (hydrogenated coconut oil) is constant. We will also investigate the effects of high (30%) and low (8%) levels of protein in these diets. We will also compare the effects of different non-nutritive fibers among them (cellulose, alfalfa, wheat straw, bran and lignin). We will also test dietary interactions, examining the effects of changing individual components (protein, carbohydrate or fiber) in what we determine to be the most atherogenic diet. We also propose to study the effects of trans fats on lipid metabolism enzyme activity and atherosclerosis.